First attempt at clarifying the current license state

For the BSD-2-Clause history of some code, I copy the approach done in
"ath5k - License clarification" [1] which was signed of by actual
lawyers.

[1]: https://lwn.net/Articles/247806/

.editorconfig

@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2015 Simon Legner <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+
 root = true
 
 [*]

.gitignore

@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2013-2017 Robin Schneider <[email protected]>
+#
+# SPDX-License-Identifier: CC0-1.0
+
 export*
 
 # Enable the following line for repositories which should track statistical data.

.reuse/dep5

@@ -0,0 +1,10 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+Upstream-Name: opening_hours
+Upstream-Contact: Robin Schneider <[email protected]>
+Source: https://github.com/opening-hours/opening_hours.js
+
+# Sample paragraph, commented out:
+#
+# Files: src/*
+# Copyright: $YEAR $NAME <$CONTACT>
+# License: ...

CHANGELOG.rst

@@ -1,3 +1,7 @@
+.. SPDX-FileCopyrightText: 2016-2021 Robin Schneider <[email protected]>
+..
+.. SPDX-License-Identifier: LGPL-3.0-only
+
 Changelog
 =========